Telephone-transmitter.



C. ADAMS-RANDALL.

TELEPHONE TRANSMITTER. APPLIGATION FILED AUG. s1, 1907,

980,042, Patented 111111211910.

z BHBETS-SHEET 1.

C. ADAMS-RANDALL.

TELEPHONE TRANSMITTER.

APPLIOATIONFILED AUG. 31, 1.907.

980,042. 4lianentedlmc. 27,' 1910.

2 SHEETS-SHEET 2.

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CHARLES ADAMS-RANDALL, or NEW YORK, ii. Y.

TELEPHONE-TRANSMITTER.

Specincation or Letters Patent. Faterited Deo, 27, 1910.

Grignal application filed April 14, 1905, Serial No. 255,302. Divided and this application filed August 31,v 1907. Serial No. 390,970.

To all whom. it may concern: 'Be it known that I, CHARLES ADAMsRAN- DALL, a citizen of the United States, residing at Nerv York, in the county of New York and State of New York, have invented'nevv and useful Improvements in Telephone Transmitters, of which the following is a specification.'

This invention relatos to telephone transmitters, and more particularly to that class adapted for use with common battery or central energy systems, and wherein currents of higher voltage are employed With the transmitters than local -battery transmitters; and the essential or vcontrolling feature ofthe present invention is means dlvided out of my pending application Se# for regulating and obtaining the proper resistance of the transmitter proportionate to the current to be employed. lrleretofore'in central energy transmitters, the resistance has had a 'fixed value, or total.. normal resistance which has been obtained, generally,

by increasing the depth of the variable lresistance, or by the use of fine granules. of-

high resistance of considerable depth, or

l of increasing the resista-nce ofthe circuit of y Which the ltransmitter is a part by. introducing into said circuit a fixed or adjustable resistance invariable "by the action of the transmitter. It has been found in such construction and adaptation that the 'varia tion of the resistanceA of the transmitter is reduced, the articulation impaired, and the output at the transmitter but slightly augmented, especially by the useof anadded,

fixed, non-variable resistance. The present ing material. lThe member 1 of the body 'or A frame carries a diaphragm 3 which. rests invention seeks to overcome these defects and objections; and to this end consists more particularly in subdividing the total normal resistance of' the transmitter into fractional parts or units, such parts or units being independent of oneanother, whenl not connected up in series,' buty arranged to be connected up in series with a source of involved in the present invention, the variation of the current is made at each fractional' part or "unit, or simultaneously at the severalnits, thereby multiplying the variation acgoi'ding to the number of parts orv units,

and Vwhereby the variation. of the current passing throughjthe. transmitter is not de.

creased, but ratrerugmented. o r `is at .least up to a maximum or highvoltage.

' the views.

equally as great, or the same, irrespective 'of the number of units or the total resistance of the transmitter at its maximum resisti ance, or, in other Words, Whether the normal resistance is high or loW. This, arrangement is of great advantage, a's the articulation is not impaired, nor the current ower or output at the transmitter decrease., and

frying or arcing is prevented.

In the accompanying drawings, the transmitter is shown as having but four unitsV or fractional parts, but it will be understoodthat the number of units may be increased with a corresponding increase of voltage The present invention embodies matter rial' No. 255,602, tiled April 14:,- 1905.

In the drawings: Figure l is a plan View verse vertical sect-ion of the transmitter.

Fig-3- is a plan vievv of a transmitter em bodyin 'the features of the invention and particu arly illustrating the d ilerent parts or units connected up in series and showing a simple multiple vform of Vswitch means.

Similar characters of. reference are employed toindicate corresponding parts in 'Ilie numeral l` designates one member ofV the body or frame of the transmitter Whichmay be made of any .suitablematerial and has securedthereto the remaining member 2 constructed of any'preferrednon-conductupon aring 4 of'rubber, paper, oi' other suitable material, the diaphragm being held against this ring by suitable spring fingers 5 projecting inwardly from the ring 1 and -of any number found necessary. The diaphragni 3 is preferably non-metallicand i may be constructed of i' glass, mica, Wood, 100

vulcanite, or otherY similar material. Secured tothe diaphragm is a series of carbon contactpieces or electrodes 6, four being shown."

The member 2 carries .adjustable metalil or carbon electrodes or'contact pieces I, preferably slightly convex at v their contact electrodes 6,*and therefore four are shown as being used in the particular transmitter construction illustrated. 'lhe electrodes 7 are held upon radially arranged metal arms 8 from which outwardly extend adjustable flat springs 9 secured to the frame 2 by screws 10 and engaged by intermediate adjusting screws 10a which controlthe' normal pressure contact between the electrodes 7'a` and 6. rThis normal pressure contact may also be obtained by gravity, as well as by spring pressure, or by both combined. Any suitable mouth piece 11 may be used with this transmitter.

rthe general plan'or arrangement of the' circuit connections is clearly shown in Fig. 1 and may be descrlbed as follows: The current coming 1n at the terminal 12 passes to a binding post 12a and from'the latten' through the medium of a wire 13, to one of the spring supported arms 8 carrying one of the electrodes 7. From this first con.

'thence by wire 19 to a binding post 18, the

circuit being completed with the battery or other source'of current supply or electric energy, by a wire 20 connected tothe ter minal 21. By this arrangement of connecting the electrodes in series., the normal internal resistance is increased and in proportion to the number of electrodes or variable resistances connected up in series, as for instance, if the wire 20 be connected to the wire 1a but two electrodes constituting a variable resistance are .in circuit and the normal resistance is lowest, and by connecting wire 20 to wire 16, it isdoubled, and with wire 20 connected with wire 17 it is tripled, and with wire 20 connected to wire 19 at'the binding post 18 it is quadrupled, giving at this lastconnection the maximum resistance of the transmitter.

While but four fractional parts or units or sets of electrodes or variable resistances are shownas lierinbefore noted, it -will be understood that any number of similar sets, solid or granular, may be used to increase the total 'normal resistance of the transmitter and proportionately with the increase of parts or units up to any required or desired normal maximum internal variable resist-- ance. The addition of `any number of similar sets of electrodes of variable resistancesY eaobaa in excess of four, as shown, will require but an obvious multiplication of the fractional parts or units. lt will also be understood that the change of connection of thewire 20 `to the diffe-rent parts or units connected up in seriesmay be readily accomplished by means of a simple multiple or four or more way switch of any of the well known forms generally used.

Fig. 3 illustrates one practical embodiment of the arrangement'just specilied, and therein the diaphragm is nonmetallic as in coperating with this diaphragm are cups having the same reference characters applied thereto and which hold the variable granular resistance material, electrodes be ing operatively associated with the cups and arranged as in the construction shown by Figs. 1 and 2. In this instance a series of switches S, S', S2 are secured on the mem ber 2 of the casing or body of the transmitter, said switches each having their respective contact buttons b, b', b3, bt, b5, be and .their respective connecting wires. A battery B and an inductorium l are also shown in this arrangement and the conne@ tions from and tothe battery are as follows: from the battery B to 12a. bl the wire 12, as in the construction shown y Figs. 1 and 2, then by wire 13 tothe top electrode 7 adjacent to 12a, the corresponding cup lor lower granular resistance material serving as a coperating electrode being connecte by wire 14C to switch S between the buttons and b. From the button b a wire 25 runs to binding post 18 and through the medium of wire 20 to the primary coil of the inductorium I and thence back to the battery, whereby only one part or yunit of the transmitter may be used.v To connect in another unit, switch S is changed or shifted to contact with the button b', being in theprevious instance placed in contact with the button Z2. Between the button b and the second elec trode 7,' a wire 14 extends, 4and the4 corresponding lower electrode 6 or granular variable reslstance material is connected 'to the switch S by a wire 16 and from 'S' through button b3 by-wire 25 back to the battery as before, thus permitting the utilization of two units and doubling th'e internal normal resistance of] the transmitter. The remaining units, two or more, are connected inseries in the Asame manner.. lt willv be seen that by changing the wire 12 to connect with any one of the switches S, S and S2, either unit can be used independently of the others.

As shown, the transmitter is connected directly in the circuit with' the source of current suppl but it will be obvious that the primary o an induction coilor transformer 1" mitter and the source of electric supply, it

the construction shown by Figs; 1 and 2, and

similar to those heretofore described andl can be included in the circuit with the transiio -units may consist of granules of carbon suitably arranged and held in any of the well knownways, or other variable resistance's may be used, the main feature being the subdivision of the total resistance into 'independent fractional arts or units, eachy unit being variable an having means coperating therewith for connectingthe'ame in-series at will or as may be desired.

What is claimed as new, is: I 1. A telephone transmitter having a, diaphragm', a plurality of independent variable resistances or electrodes carried thereby and insulated therefrom, a corresponding plu-.

ra'lity of independent coperatin electrodes insulated from' one another and from the diaphragm and engaging the said independent variable resistances or electrodes car` ried by the diaphragm, and means for resist-:mees or'electrodes carried by the diaphragm and' the independent coperating electrodes engaging'. therewith whereby the internal resistance'of tlie,ti'ansinitter may' be varied.'`

2. A telephone transmitter having a given variable resistance subdivided into fractions. or units,-a vibrator', each unit being insulated rom the vibrator and having its own variation produced by said vibrator, the vibrator-being common to all the units and another', contact means and a source of current supply with which the units are adapted part, and adjustable mea-ns also connected to portions ofthe unitsvand coperating with the cont-acts.

my nand in presence of two subscribing witnesses. v

CHARLES ADAMS-RANDALL. Witnesses:

DOUGLAS Swir'r, JOSEPH FIELL.-

connecting in series, in whole or -in part, the

In testimony whereof have hereunto set the latter normally insulated. from j one Y to 'De connectedupin series, in whole or in 

